They're not the easiest to sex. And since these are both my first monitors I don't have a lot of experience sexing them. But what's weird about Ackies is that they usually change sex when young. The dominate one in the group will turn male while the rest turn female. So if one was to buy 3, week old baby ackies, the group should turn into one male and two females. When I was given these my buddy thought one of them might be a male already but I guess that's not the case. Either or, you never get an overabundance of males when you buy them in groups.